krb5/Use-k5_buf_init_dynamic_zap-where-appropriate.patch

From c5df16a88027d7f9b6eb53b1c3fa949d6538616b Mon Sep 17 00:00:00 2001
From: Greg Hudson <ghudson@mit.edu>
Date: Mon, 26 Mar 2018 11:24:49 -0400
Subject: [PATCH] Use k5_buf_init_dynamic_zap where appropriate

(cherry picked from commit 9172599008f3a6790d4a9a67acff58049742dcb6)
---
 src/lib/krb5/ccache/cc_file.c    | 4 ++--
 src/lib/krb5/ccache/cc_keyring.c | 2 +-
 src/util/support/utf8_conv.c     | 4 +++-
 3 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/lib/krb5/ccache/cc_file.c b/src/lib/krb5/ccache/cc_file.c
index 6789c09e1..9263a0054 100644
--- a/src/lib/krb5/ccache/cc_file.c
+++ b/src/lib/krb5/ccache/cc_file.c
@@ -758,7 +758,7 @@ fcc_next_cred(krb5_context context, krb5_ccache id, krb5_cc_cursor *cursor,
 
     memset(creds, 0, sizeof(*creds));
     k5_cc_mutex_lock(context, &data->lock);
-    k5_buf_init_dynamic(&buf);
+    k5_buf_init_dynamic_zap(&buf);
 
     ret = krb5_lock_file(context, fileno(fcursor->fp), KRB5_LOCKMODE_SHARED);
     if (ret)
@@ -982,7 +982,7 @@ fcc_store(krb5_context context, krb5_ccache id, krb5_creds *creds)
         goto cleanup;
 
     /* Marshal the cred and write it to the file with a single append write. */
-    k5_buf_init_dynamic(&buf);
+    k5_buf_init_dynamic_zap(&buf);
     k5_marshal_cred(&buf, version, creds);
     ret = k5_buf_status(&buf);
     if (ret)
diff --git a/src/lib/krb5/ccache/cc_keyring.c b/src/lib/krb5/ccache/cc_keyring.c
index fba710b1b..8419f6ebf 100644
--- a/src/lib/krb5/ccache/cc_keyring.c
+++ b/src/lib/krb5/ccache/cc_keyring.c
@@ -1295,7 +1295,7 @@ krcc_store(krb5_context context, krb5_ccache id, krb5_creds *creds)
         goto errout;
 
     /* Serialize credential using the file ccache version 4 format. */
-    k5_buf_init_dynamic(&buf);
+    k5_buf_init_dynamic_zap(&buf);
     k5_marshal_cred(&buf, 4, creds);
     ret = k5_buf_status(&buf);
     if (ret)
diff --git a/src/util/support/utf8_conv.c b/src/util/support/utf8_conv.c
index 5cfc2c512..08cef4168 100644
--- a/src/util/support/utf8_conv.c
+++ b/src/util/support/utf8_conv.c
@@ -99,7 +99,9 @@ k5_utf8_to_utf16le(const char *utf8, uint8_t **utf16_out, size_t *nbytes_out)
     *utf16_out = NULL;
     *nbytes_out = 0;
 
-    k5_buf_init_dynamic(&buf);
+    /* UTF-16 conversion is used for RC4 string-to-key, so treat this data as
+     * sensitive. */
+    k5_buf_init_dynamic_zap(&buf);
 
     /* Examine next UTF-8 character. */
     while (*utf8 != '\0') {